WHO: Cut Antibiotic Use in Food Animals

Guidelines would ban growth promotion with antimicrobials

It's time to limit the use of antibiotics in food animals in order to prevent the rise of antimicrobial-resistant strains of pathogens that could affect human health, according to the World Health Organization.

In new guidelines, the agency urges an "overall reduction" in the use of all types of medically important antimicrobial agents in food animals as well as bans on some forms of use.

In particular, the guidelines recommend a halt to the use of antibiotics:

To promote growth of food-producing animals

To prevent infectious diseases that have not yet been clinically diagnosed

On the other hand, using the drugs to treat animals with a diagnosed disease or to prevent its spread once diagnosed should be allowed -- but not with antibiotics that the agency called "critically important for human medicine."

It's an open question how widely the guidelines will be applied, commented Dimitri Drekonja, MD, of the University of Minnesota in Minneapolis, a member of the public health committee of the Infectious Diseases Society of America.

Public opinion, in the U.S. at least, is in favor of reducing non-therapeutic antibiotic use in meat animals, Drekonja told MedPage Today, "and I think industry has more or less acquiesced to that."

Indeed, he noted that some food chains now brag in their advertising that they don't use antibiotics. And the shift in public opinion is not limited to the U.S. In 2006, the European Union banned the use of antibiotics to promote growth in food animals.

But it's hard to know how to allow therapy while still avoiding inappropriate use, Drekonja said. Too low a clinical bar, he said, could allow producers to observe the letter of the guidelines while still overusing the drugs.

The WHO says it considers quinolones, third and higher generation cephalosporins, macrolides and ketolides, glycopeptides and polymyxins to be "last-resort treatments for multidrug-resistant infections in humans" that shouldn't be used in food animals.

But that distinction is problematic, Drekonja said. The idea sounds "inherently plausible," he said, but it's known that pathogens can share gene sequences, so that resistance to drugs not used in humans can sometimes lead to resistance to drugs that are.

"We should be striving for reductions in all classes," he said.

The guidelines were announced as researchers supported by the WHO reported online inLancet Planetary Health that restrictions on antibiotic use in animals lead to substantial reductions in antibiotic resistance.

In a systematic review and meta-analysis, investigators led by William Ghali, MD, of the University of Calgary in Canada, found that interventions that restrict antibiotic use in food-producing animals are linked to a reduction in antibiotic-resistant bacteria in the animals.

The absolute risk reduction varies between 10% and 15%, they reported, depending on the antibiotic class, sample type, and bacteria under assessment. There is also evidence of a similar effect among humans, "particularly those with direct exposure to food-producing animals," Ghali and colleagues reported.

The WHO helped develop the study and peer-reviewed the search strategy, Ghali and colleagues noted, but had no involvement in data extraction or interpretation.

The agency "does not expect the world will change overnight," according to Kazuaki Miyagishima, MD, PhD, director of the agency's department of food safety.

But, he told reporters in a telephone briefing, food producers currently overuse antibiotics dramatically, to the point where in some countries 80% of the drugs dispensed are used in farming.

"The majority of those antibiotics are the same or in the same classes as antibiotics used in human medicine," he said.

Inappropriate use in animals -- just as in humans -- can lead to antibiotic resistance, he said, which has emerged in recent decades as an important problem in human health, where so-called super-bugs are now acknowledged as a major threat.

Miyagishima said other approaches to animal husbandry -- including better hygiene, less overcrowding, and improved sanitation, as well as vaccination -- can replace much of current antibiotic use.

"We need to take action in animal production to protect -- finally -- the public health," he said.

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